Combustion control



Oct. 6, 1931. M. G. BENJAMIN 1,826,644

COMBUSTION CONTROL Filed Oct. 4, 1929 2 Sheets-Sheet l INVENTOR ATTORNEYS Get. 6, 1931. M. G. BENJAMIN 1,825,644

COMBUSTION CONTROL Filed Oct. 4, 1929 2 Sheets-Sheet 2 INVENTOR Merrill CiBqy'am/n.

ATTORNEYS Patented, 0a, 6, 193,1

PATENT arsen m -1G. BENJAMIN, or 'LAKEWoon'on o 7 COMBUSTION CONTROL ln plieatiohffiied October 4, 1929; Serial No. 397,433.

; vlvfvfinvention pertains to systems forcontrolling combustion and. in partlcular, to systems cf the jtypementioned Wlnch are appiicabl e to the furnaces of a steam-boiler plant-. p

Theprincipal objectyof my'invention is the provision of acombus'tion-controlsystem that shall be entirelyautomatic in its operation. a v

I Another object of my invention is to pro vid'e acontrol system which shallbe responsive to'the steam p'ressurejm a boiler or in the output main connecting a plurality of boilers, if such is provided, and shall'operate sure therein. V

Another oogect'ofiny invention is to proto maintain a constant predetermined presvide a 'controi systemin Which a variation '"insteani pressurev causes the operation of means, such as boiler andfurnace auxiliaries, to restore the steam pressure to its normal value, the speed ofltlie variousauxiliarycontrolling means lb eingwmade proportional to the ma nitude of the variation of the i Y b steam pressure from normal. 7 h

Another object of'my invention is to pro-,

vide means for decelerating the adjustment of 'tlie boiler and furnace auxiliaries When' 1 thes teampressure tends to return to normal. 7 '11 An other' object of my invention is to, proating means at-a central point for the-adjustment of. a plurality of boiler and furnace auxiliaries;

' Another 'cbject o'fjmy'invention is to provlde means for supplementally controlling the adjustment of thevariOus auxiliaries in flacc'ordance with certain functions of the boiler, and furnace which Will'bedescribed in'more detail hereinafter. j

,; A un further object of my. inventionis to.

uti ize the "characteristics or; a'jturbo-generaito'r unit for drivine one offthe auxili'arie'sof q 4:- upplying cur rent a boiler furnace as Well. as a generator "for r to motors drivlng other auxiliaries thereof.

I'am aware" that-it has previously been proposed to control the forced draft sup-f plied to'a boiler furnace by varying the'posi tion. of an inlet damper or by varying the? speed of a forced-draft fan-in-accordance with the boiler steam pressure and that the control'of the induced draft by similar means has also been suggested. I understand, also,

described and claimed in my copending application Serial No. 323,145.

In accordance with the system of my invention, I provide a motor-driven, forceddraft fan and a turbine-driveninduced-draft fan, as Well as a motor-driven stoker'or, equlvalent fuel-feeding means. The turbinefor driving the induced-draft fan serves also to drive a direct-current generator Whichis I utilized as a source ofienergy for the motors 7 driving the forced-draft fan and stolre'r 'or other fuel feeder. As the induced-draft fan requires a greater amount of energy than any other aux1l'1'ary,I propose to drive this unit FFECE by a turbine and make use of the same instru-v Y mentality to provide "direct current for the. other auxiliaries. The advantage resulting fromthis method of operating, obviouslyyis that direct-current control for auxiliary motors is much simpler than that for alternating-current motors. It is possible,

furthermore, by regulating the speed of the turbo-generator, to control the speed of the other auxiliaries so as to provide an improved method of control. Byvarying the speed of these auxiliaries properly, it is possible, of

course, to control th'e rate of combustion in a boilerfurnace. Asthe system of my inven tion Willgenerally be applied to a battery of boilers, such as is usually installed in a steam electric generating plant, my invention contemplates the duplication of the control apparatusto be hereinafter described for one boiler, foreachof the boilers in the'batt'ery.

As ameans for controlling the speed of the boiler and furnace auxiliaries, I have disclosed the rheostatic control of the shunt field-magnet windings of the motors driving 1 steempre'ssure, nay-system includes edldi-l beeinployed.

m vary the speed 'ofthe auxiliaries, in inverse 1 zsternoi mvi vention, referenceshonld bel d Fig 2 illustrates the -control eduipment for I I the stoker motorof theboilershown t indicated genemuy, at f p e t 5 arranged to drive similar-1 auxiliaries of the i --furnece"11. ;Themotors ma beconbledfto the auxil aries by zinv'kn'o'wn drivingin certainofthe' auxiliaries and the usual valve contr ol'of the turbine driving the induced:

draft fem eilthoughit isobvious that any other known method; ofsgeed control for {electric motors .or' other driving" meens may For the primary control oi": the speedofthe i means for driving the auxil aries, I employs steam-pressure regulator which operates to proportion to: the pressure the steam in the boiler or steam header, to vary the rate of combustion ine similar ratio. Inaider Ition; to the primary control by means of the tionalsupplem'en'tal-v controlling means for "the various 'iuxilia'fies, independent of the steam-pressure regulator and of each other.

forf independently, controlling thespee'd of f 'auiiiliery' of ziny furnace, These supple mental control 'means "are respons-ive to certain boiler 21 d furnace'conditiohs whichwill b d ibdfindetail later.

Foremoreoo v 4 plots descriptionof the sys-Q T'to the follo'wingspecificetion endthe scam;

panying drawings, in which 1 Figure-.1illustrates,idiegramro etically, one .ofa plurality of vboilers, together ivithlthe control equipment six theIforced-draft end induced-draft fan inloltor sjthercof "ind the ;'i d eswrs t ererer,an '1 -and the masterv steftmiiressure regul 'torq 7 wellfa's gt second boiler which s adapted;to have sim lar control equipment a ssoc ete'd fReferring now in detail to 'both figiires of' 4d the drawings furnaces liO'end 11" sreiadapted "to'gencratecsteemdn boilers 12 ,2-d 13, for V p yi YWP e d; l 'b fe shown), for efiampl onnectedto'thefsteem. heederle'e if The furnace 10 is; provided with. s ino'torfl d "ven; .fuelfeeder h be e-sthker;v Q feederfor-pulverized fc'oel', endelsoliwith a orcedFdraftjfanQItSQsnd' en induced-draft r feni 17;.The furnecelll is providedfwith; so similar eux'iliaries namely 5a istolrer .18;; y forced-draft tan -19fendinducededrett fan 20. Electric} motors21jen'd'23 are provided for:

driying theforcedgdreftfen;thestoher of the "furnace 110, andsiiniler 'rno 5% end dare but I'he-ve illustrated thev euXi-liz'irie, directly ,7 connected to the shafts of the motors. For drivingthe induceddrz ft'fen 17: provide" l esteem; turbine f22 which is edented to be supplied with steam I-from thel h s der;

u'nder the'controlof e regul n5: elx' eff28. In additionftodriving the induced-draft fan, 5 the turbine 22 driyesf also *2; direct current I J The speeds of the. auxiliary motors generator 25 which of the combound- Froinfthis point'on, the description of my invention will refer; only to the. auxiliaries of the furnace 10,"?17 being assumed'thet du-- plicate controlequipment will be provided for the auxiliaries of the furnace 11.

23 which drivethe forced-dre'ftfan' and the stokerofthe furnace 1(),' are' controlled by rheostats 27 and 29", although; asebovestated, any eqtiivelen t s ieed-co'ntrollinggmeans may be substituted." The speed of the turbine 22 is governed by the setting ofthe valve'28icon-1 trolling the. admission of steam from the header l l to the turbine, in a manner which willbe described more fully hereinafter; V l

-'Asindiceted at the beginning. of thisspecificationiit is the object. of mvinvention to provide for the adjustment-of thespe'edslof the z uxiliary motors in a'ccordance'wit" the jfverietion in certeinboiler and furnace this variation is accomplished willnow be de scribed n detail.

Connected to thesteamheader is e header. fThe master .steam p ressure regulabe controlled by the Bourdontub'e; This regulator comprises ashaft 32-011 which is the Bourdon tube by means of a link 34s A contact-bearingdisc35 is also mounted on the'sheft 32 and is provided with teeth on its periphery for engagement with a worm A contaict arm 37 is mounted on the shaft 32 and is adapted to be frictionelly engaged by the disc .35"androtetedtherewithiuiitil it engages eitheroneof the fixed contaotsi38, 39. j

2i and 7 ii the steam-pressure and also in accordencelwith conditions. The'enact mechanism by which The worm-wheel disch35is brovided' -with Q two'conducting segmentsA-O end 4l, -s ei 3erate d bvian insuletingfspecer, whjic'h are adapted to be enge'gedby thecontact arm 33 when the latter; s moved in either direction from the central or neutral position in which it'is illus The ,c ontecterm 33, under the "iniiuenceoff the 'B urd n tube 30, is'ejdep'ted to control the operetion'of mjInQt r-'EZ havingiforwardand r reverse field windings 43 end ll." Themotor will be referred to lhereinetter'as the in dlcator -generetor motor because it isv directly connected to the rotor of a. synchronous, poly- Qphe'se, alternating-current machine l5 which 77 serves to supply current to otherelectrioal de-. 5 vices, as will be explained more fully inthe v course of the following"description; It may be. noted, Ll oivvever j at this point, I that the stator of the machine is adapted to been- The a pair of contact arms 48 and49 which engage stantly other polarity will exist thereacross.

resistors: 50 and 51. These resistors have their corresponding terminals connected to current I therefore, that the setting of the rheostat 29 sources of opposite polarity and thus constitute a so-c'alled potentiometer bridge. .It Willbe obvious that, when the arms 48 and 49 take up the neutral positionin which they. are illustrated, the voltage difference therebetween will bezero and'that, as the arms 'move simultaneouslyin the one or the other direction from the neutral position, a conincreasing voltage of the one or the The voltage across? the arms 48 'and49 is i applied'to the armatureof'a motor 52 having a shunt field winding The motor52 is mechanically connected tothe rotor of an alter nating-current machine 54, similar in all respects to, that shown at 45, which will be referred to as the control generator, since it supplies current tothe conductor 56 which tative movement.

constitutes a control bus.

It may be desirable to employ a speed-reduction gear between the motors 42 and 52: and the generators 45 and 54, since the latter.

are designed only for a relatively limited ro Referring again to the contact arm 37, this member is adapted to complete a circuit for a relay 57 when it engages either of its assocompleted throughthelarm 87; one orithe ciate'd fixedcontacts 38, 39. The relay 5?,

when energized, operates to shuntia resistor 58in the circuit of the field winding o3 of the motor 52, in orderto decrease the speed of the lattjer in accordance with certain conditions to be described later. Therelay' circnit is otherfof. contacts 38 39, one or the other of a pair of contact segments 38 and 39 con nected thereto respectively, and mounted onthee-me 35, and a fixedeontaet roller 3?- adapted to engage eitherf'of'the segnients l and 39, depending on the position of thefdisc 35. Whenever the latter is outofnits neutral position, only one of the-segments is engaged by the roller, the other remainingim tion of the control motor 23.- I p 7 the motor 23, in addition to effective. The purpose of this construotion will appear subsequently;

[Thefshaft of g Y being'connected to the stoker 15, hasa'n err-i A I tension'to the operating' arm of the speed-j a controlling rheostat 29.; The connectionbetween the motor shaft and the rheostatarm,

however, is not permanent'but is adapted to be-eli'ected, when desired,byi means ofa mags steam regula-- ard des'ignand is adapted to be controlled by solenoids 61 andl62. .lVhen one of said solenoids is energized, the clutch 60 so connects the rheostat arm to the shaft of the motor 23 that it is rotated in one direction.

Energization of the other solenoid of the clutch-will cause rotation of the rheostat arm in thereversedirection. It .Wlll be obvious,

and, consequently, the speed of the motor 23, may be varied at will by the successive energization of the solenoids 61 and 62 of the clutchfSO. Instead of the magnetic clutch I may employ a separate reversible motor for operating the .rheostat 29.

For controlling the solenoids of the clutch. 60, lprovide a contact-making mechanism incheated generally at 63. This mechanism includesa disc 64 provided with two conducting segments 65 and166, insulated from each other,

which are'adapted to be engaged by a contactv arm 67whieh is actuated in accordance with the movement of shaft 29 on which the contact arm of rheos'tat 29 is mounted. The disc 64 is mechanically coupled to the rotor of a polyphase, synchronous, alternating-current,

machine 68 similar to those shown at 45 andtionary in corresponding positions. This synchronizing action is well known and has been employed heretofore where it was desired to move one element in synchronism with another- The theory underlying this operation. is known. and therefore, needs no explanation here. t is sufficient to explain that any movement of the rotor of the genera tor 54 will immediately be communicated to the rotor of the-motor 68' and. therefore, to the contact disc 64. The positions of the disc 64 and the'contact arm 67. on their respective driving shafts may be'reversed if desired.

The motor 68, however, differs from the generator 54 in that the statorwinding of the motor68 is adapted to be rotated by means of a worm 69, the motor housing being supported for rotation and provided at its periphery'wit'h teeth for engagement by said worm.

It'will be obvious, of course, that the position'ofthe rotor of the motor 68 is controlled not only by the position ofthe rotor of the generatoro i but also by the position of the statonof the motor 68. That is to say, the rotorof the motor 68 may be shifted as a result of a shift inthe position of the rotor of the generator 540i a shift in the position of the stator 68.- V

. The worm 69 is adapted to be rotated by the movement of the shaft 29 which carries 1 the contact arm ofatherheostat The con- V nection of'the worm 69 -to the shaft 29,how

ever, is notpermanent butis' effected only when the solenoid-70 of a magnetic clutch 71 is energized. A= inan'ual switch is pro-'- 'VlCled ijOY-COIltIOlllIlg the energization of the solenoid 70- in lseries with either o f'the sole V noidsfilarid 62 of the clutch 60'a'nd," inaddi titans balancedrrelay 7 3'is also effective *to "The relay 178 comprises a pivoted beam I adapted to be actuated bya plurality of mag-' control said solenoids.

neticoils 74, 75; and 76. The coil 74 is connected' in circuitwith a rheostat 'Z'Lthe'contact arm-of which is driven by the shaft 29. LThe energization ofthe coil 74, therefore,yaries directly with the speed of the Stoker*moter23 which, aspointed out prev'i ou-sly, responds directly to variations in the steam pressure in the header. 14.1Y-The coil 7 751s energized under the control of a steam- I flow meter78 whichisso connected as'to meas- 'ure the steam-output'of the boiler 12. The

r not shown, through the pipe 80.

coil 7 6 5 similarly, is energized under the control of. a feed-waterinput flow meter 79 which measures the flow of feed waterinto the boiler 12. It will be understood that the I feed water is supplied-to the boiler'from the usual feed-water heater by means of a Thesteam-fiow meter '78 and the feed water flow meter 7 9 are standard devices and are, therefore, not described in detail.

'Anindicating panel 81 maybe provided with a plurality of indicators fOIfCOHlHlUDJ- eating to the operators ofthe stationa knowledge of the ad ustment ofthe various auxiliar'ies. One-of these indicators 82, is prothefcohtrolbushbff vided with twosnointers, oneof'which is actuated by the indicator motor 84 connected vto: the indicator bus 46, the other beingactit ated "by "the indicatorymotor 83 connected to The-motor 83 moves in synchronism with p I moves n syn chronisin with the generator 54.

- The two'pointers'son the' dial82;theref'0re',

the generator 45, and'the motor -84, similarly acquaint the station-operators with the actual steam p rcssurein thehe'ader and the adjust inent of the speeds of the various auxiliaries to restore the pressiireto normal. J I I V "Theindicator 85is driven by theindicator I motor'86 which is-connected to the rotor of a an indicator -;generator 8'7 *mountedpnthe shaft 29". The indicator 85 therefore; always shows'theposition of the rheostat29'which controls thespeed of the stolrer rnot'or23L V Havingdescribed the master control reg-- ula'tor and the control apparatus for the 60 "stolrer motor inlzdetail, I shall now explain the m'ethg'id (if-operation ofmy-systernr i In this description, it will be assumed first that the steam pressure in the 'h'eader14 is at its normal value, that-the steampressure reg ulator31-iandal l ofits elementsare in their in the neutral trol panels a. p a Q 7 I The motor 52', being subject to: the differspeed of the motor-1,52,

neutralpositions, that the motors 42 and 52' are stationar dfl t t t ,1 ,is rotating at normal Speed, ,r

ficient fuel is supplied to'the grate to maintain normal boiler pressurelfor normal deinandi'on thest'ation :It will also beassumed that the contactmeniber ofthe relay 73 is position, aswfell as theswitch. 72 and the contact'67.- j I V i If the boiler pressure falls abelow its nor.- Inalvalue; ass result of an increase in the station load, for-example, theuBourdon tube 30 will contract. anclQthrough'the link' 34,

will cause the contactarnr38' of the pressure regulator 31 to engage the segment 41; ,n This resultsin'the completiongof'a circuit through the forward field winding 43 and armatureof the motor'42 which thereupon begins torotate..' As-the motor 42rotates; it shiftsithe position of the rotorrof the indicator generg ator45'yshiftsthe arms 48 and 49 OfTTBSlSiZOTST 50-and 51 away frorn'qthe fneutralposition and, at the" same tin1e,.'iten ds to restore the disc 35 to aposition inwhich the arm 38 engages the insulating spacer between'the conducting segments :40 and 41. When this restoration has been; accomplished, further =rotation of the' notor 42 is stopped. The shift- 7 ing of the rotor ofthe generator :451causcs a corresponding shift in theposition ofthe pointer actuated by the motor 83 on the con ence involtage across the arms 48 and 49,

continues to turn the rotor of thecontrol ,gen-

erator 54. The rotor of the generator 54 causes a' corresponding shift in the 'pos1t1on' of therotor. of the motor 68 which thereupon 'mo ves the discf64 so that the contact arm 67 engages one ofthe'conductingsegments 65, v66. *A circuit is thereby completedgforone Qneutral position between-the segments 65 and-66 andfurther adjustment of the stoker motorrheostat is stopped. -,,The movement of the 'rheostat'garm 29 is indicated-on the a board 81 by means of theindicator motor 86 and the-indicator 85. c- The control-generator motor 52continues the header 14 begins to increase toitsnornial Value: When I this result occurs; the a contact arm33 of the master regulator 3l'engages the contact segment40'to'causea reverse rotation of'the motor 42 and a decreaselin the to 'shift theposition of the rotor of the con- 'ytrol generator'54 until the steam pressure in If the restoration of the steam pressure proceeds at a rapid rate, the contact arm 37 will-engage the fixed contact 38 to energize the relay 57 which short-circuits the resistor 58 in the circuit of the shunt'field winding 53 of the motor 52 to'further' decrease the speed of the latter. If the restoration of the 7 slow rate, however,the speed of th m t pressure and normal pressure.

isdecreased only by the return of the rheostat "arms 48,49 to the neutral position. In any case, the speed of the motor 52 is dependent upon'the difference between the actual header "Upon the occurrence ofa sudden change in steampressure, it IS desired that adyu'stment of the auxiliaries proceed at maximum speed. The construction of the contact arm 37, the segments 88- and 39, and theroller 37;, in connection with the contacts 38 and 39, insures that, under-such conditions,- the "speed-reducing effect ofthe operation of the relay will-"be prevented-until the restoration 'The reverse rotation of the'motor'52 causes of normal conditions has actually'proceeded to a' substantial extent.

an adjustment of thejstoker-motor rheostat 29in the reverse directiont reduce'the motor speed'to normal. e i

i In the'preceding description of operation, no mention has been made of the relay 73. This relay, however, performs an important function. I It operates to control the speed of the stoker motor supplementally so: that the motor speed will be further adjusted in accordance with I conditions in'the" boiler 12.

If the quality of the fuelsupplied 'to the stoker 15 varies, for example, the actual amount of combustible fuel supplied to the grate will likewise vary.- If coal of a'lower grade is placed in the stoker hopper, less heat will be-supplied by the furnace to the boiler and less steam generated thereby. The

steam output oftheboiler will therebybe decreased andthis decrease will be registered by'a change in the energization of the coil 7 5 which is controlledby the steam-flowmeter 78. Thischange in -the energization' of the coil 75 of the relay 7 3 will cause the, pivoted beam of s-aid'relay to'inove so that its contact arm will engage one of the fixed contacts to energize the coil of the clutch 71 in series with one ofthe coils 61, 62' or of the clutch 60. y

The energization of the coils61, 62wi1l 7 cause an adjustment of the stoker-motor rheostat29, as explained heretofore. The

simultaneous energiz'ation of the coil 70 will cause a shift'in the position of the stator of.

the motor 68 which has'theelfect of further adjustingcthe position of the Stoker-motor rheostat through the contact mechanism 64; to 67'. It will thusbe apparent that a change in the grade of thefuel supplied to thefurnacewill cause a change in the Stoker-motor speed so that more or less coal will be supplied per unit 'oftime to compensate for the decrease in the percentage of combustible matter in the coal and to maintain a constant supply of combustible matter per unit of time forany given'setting of the master 7 regulator. steam pressure proceeds at a comparatively A similar result is effected by a change in the rate of feed-water supply. Ordinarily, feed water is supplied at a definite rate and at adefinite temperature. If anything happens to vary the rate of feed water supply, for example, the failure of the feed-water pumps (not shown), the energization of the coil? of the relay "4"3-will be so changed by the operation of the feed water flow meter .79 as to adjust the setting of the stokerboiler operation. The amount of fuel supplied to thefurnace, 1n other words,'is varied in accordance with the amount of heat absorbed by the boiler.

. The manual switch 72 may be employed to effect the control of the stoker-motor rheosta-t in the same manner as that described heretofore in connection with the'relay 73, the con- 'tacts of'the switch 72 being in parallel with those of the relay 73. The switch 72 may preferably be mounted on the control panel 81 instead of in the position shown.

Thecontrol of the forced-draft fan motor 21 is effected in a manner similar to that described above for thepstoker motor 23, the

only difference being in the functions of the boiler and furnace to which the supplemental control for these auxiliaries is responsive. Tlhespeed of the forced-draft fan motor 21 is adjusted in'response to the movements of the master steam-pressure regulator 31 in identically the samemanner as the speed of the stoker motor. The supplementalcontrol of'the speed of the forced-draft motor is,

however, effected by a balanced relay 87 which comprises a pivoted beam and solenoids 88, 88" and 89 for actuating a Contact armv mounted on the'beam into engagement with one of two fixed contacts 90. V Thesolenoid 88 is energized in accordance with the power inputto the forced draft fan motor 21, being connected to a shunt 91 in the motor circuit or other equivalent power-measuring device. ".lhes'olenoid 89 is energized in accord'ance with the operation of an air-presjiao 5 draft fanmotor, therefore,*n1ay be said'toibe responsive to the difference between the pow r a draft air pressure- 15- suresr'egulator 92 which is similar, to the steam-flow meter 78 .inthat it produces an electric current proportional to theair1 pressure I in the duct between the :fan l6 and the 'ashpit of the furnace 10; The solenoid 88,

iscontrolled by a .rheostat 89 actuated by the samemeans employed for the control of the rheos-tat 27 or" the forced-draft fan motor Q The "control of; the forceder; input togthe fan motor and, theforced- By employingthese functionsy it possi 7 bl e, byvpropercalibrationlofthe relay 87,:

to maintain a constant rate of air supply to.

furnace, thatis to say, the we'ightrof air supplied. per minute is maintained'constant,

at'therate fixed by thepositionof the master regulator, for all conditions of boiler load.

fiiflhe speed controlof'the turbine 22 which cl-r ives the induced-draft fanl'f'randthegens.

erator 25. .is efiectedj-by the master steam pressure regulator through a'combmatlon of self synchronous motors, electromagnetic t [clutches andmechanlcal connectlons thereloetween inthe form of shafts and gearing, 1n

the same manner as that described forthe control ofthe speed of the stoker motor 23,

except 'thatthe controlling unit is the valve 328 which governs the admissionof steam from the header 114: to the turbine-22 instead of.a-rheostat, such as that'shown at 29, for

controlling the speed ofthe motor 23through changes in the GXCl j tation of its shunt fieldmagnet windingt o v 1 v The supplemental control of the turblne 22 which drivesinduced-draft fan is effected by a furnace-pressure regulator 93; This de-.

vice comprises a bell floatwhich is afiected by thepressure of the-gasesin the combustion, chamber of theifurnace 10, to increase the speed ofthe turbine 22rby't-h'e same means "describedinconnection withthe stoker motor,

when the furnace; pressure tends toin'crease." The furnace pressure, therefore, 1s ma1ntained at substantially a constant valuegsmce an increasetherein tends to increase thespeed of the turbine 22 and the induced-draft fan which tendsto decrease the furnace pressure; It will beunderstood, of course, thatyif the head'er'pressure' increases above "normal, acorrespondmg ad ustment of all the boiler and furnace auxiliaries will be eifectedto decreasethe rate of combustion; o i The positions ofthe, rheostat- 27 valve 28 which' ,controlfthe speeds of the.

forced-draft fan motor 2l and the turbine '22 maybe indicated on the control panel 81 byfthe indicatorstlt and 95which are driven I by the indicator motors 96 and These motors are actuated; respectively, by the indicator generators 98 and' 99' which. are memammary coupledto the rheostati27land the g valve 28.- V As previously. stated, the controlequipmerit-illustrated and described for-the auxiliariesof the furnace lO are to be duplicated Tm for the-auxiliaries of the'furnace 7-11. It is 7 to be understood that all auxiliaries of all boilersare simultaneously controlled by the 'master jpressure regulator- 31c and that the speed of any auxiliary of any boiler; may be T7 adjustment of anyauXiliary; a, v

,An additional advantage of the system a shown and described her'einisf-that theuse of a variable speed compound -wound generator in connection with'variable speed compound- 7 vwoundfmotors; makes possible the design of the various'units of the system insuch man- A ner asto takeadvantage of the inherent characteristics of this type ofmachines for the purpose of accuratelycontrollingthe operation of boiler andfurnace auxiliaries.

A further advantage of the system o'fmyf inventionis the fact thatit is possible toutien by theturbine 22, as a motor to drive; the

-fan17 int-case offailure of the turbine, from a separate source of direct current. It is also 7 possible to providemeans for connecting the motorsidriving the other auxiliaries to sub-; stitute sources of current so that thelr operation will not be'suspended because of a failure of. the turbine or the generator. Apossible further modification would be to connect thef'generators of all the boilers correspondingtoithat shown at 22 for the boiler 5 25, in parallel, so that failure ofthe turbine of .oneboiler would not prevent o'peration'of the jotherauxiliaries thereof. 1 r v "Althoughl have shown and described only a single embodiment of the system of my invention, it; is not my intention to be limited flize the generator 25, which isnormally driv-' thereto since my invention is susceptible of "115 various changes and modifications.

It is to be particularly understood that the application of the system is not limited to installations of two boilers but may be ex- "tended to control automatically almost any number of boilers and furnaces. :Asalready a a stated the sec e of m invention is n t to andthei "P y i 0 be limited-by any of the; details ofthe show;

ing and" description but onlyjby the terms of theappendedclaims. 1;

I claimas my invention} 1 l. A control system for a plurality of boiler and furnace auxiliaries including forced-draft fans and stokersf comprising a master steam' regulator responsive to the pressure in said boiler, for directly controlling the speeds of said auxilianes, an induceddraft fan, a turbine for driving said fan,

means actuated by the master regulator for con'trollmg the admission of steam from the boiler to said turbine, motors for driving said directly controlling the speeds of the auxiliaries, a turbine, an induced-draft fan driven thereby, means actuated by said regulator for controlling the admisslon of steam from said boiler to said turbine, motors for driving said auxiliaries and a generator driven by said turbine for dr1v1ng said motors.

3; Anfautomaticsteam-generating station comprising a pluralityof furnaces and boilers 'adaptedto supply steam to a common directly controlling said fans'and stokers for I load, individual fans and stokers for supplying elements of combustion to each of said furnaces, a master steam pressure regulator said boilers, a turbine for each'of said boilers, means responsive to said regulator for controlling the admission of steam to said turbines, induced-draft fans driven by said turbines, motors for driving said first-mentioned fans and stolzers and generators also driven by said turbines for supplying energy to said motors.

4. A system of automatic combustion control for a boiler and furnace including a master, regulator responsive to steam pressure, aforced-draft fan and a stoker directly controlled by said regulatorfor supplying elements of combustion to said furnace, an

induced-draft fan for Withdrawing the products of combustion from said furnace, a'turbine controlled by said master regulator for driving said fan, motors for driving said forced-draft fan and stoker, and a generator dr1ven by said turbine for drivlng said motors.

5. In a system for steam generation, a

boiler and furnace, auxiliaries individual thereto for supplying elements of combustion and removing products thereof, including forced and induced-draft fans and a fuel feeder, aturbine for driving said induced- 7 draft fan, a generator driven by said turbine and motors driven bysaid generator for operating said forced-draft fan and fuel feeder, and a master steam pressure regulator for controlling the turbine, forced-draft fan and fuel feeder directly and the two latter indirectly through the former.

6. The combination With a plurality of boilers and furnaces adapted to supply steam to. a common load, auxiliaries such as forced and induced-draft fans, a fuel-feeder and a turbo-generator, individual to each of said boilers, said turbo-generator being mechanically connected to the induced-draft fan and electrically connected to said forced-draft fan and fuel feeder and means responsive to the steam pressure in said boilers for controlling the speed of said turbo-generator, Whereby'to adjust the rate of operation of said auxiliaries, and for simultaneously controlling individually the forced-draft fan and fuel feeder.

7. In a power system, a boiler and furnace having fuel and air-supplying means and means for Withdrawing products of combustion, a generator for driving said fuel and air-supplying-means, a turbine for driving said generator and said Withdrawing means, and means responsive to the pressure of steam in said boiler for controlling the admission of steam to said turbine, and for simultaneously controlling individually the forced draft fan and fuel feeder.

In testimony whereof I have hereunto set my hand.

MERRILL G. BENJAMIN, 

